kernel.git/arch/x86/kernel/setup_percpu.c, branch linux-2.6.30.y

x86: Remove remap percpu allocator for the time being

2009-05-25T03:37:55Z

Remap percpu allocator has subtle bug when combined with page attribute changing. Remap percpu allocator aliases PMD pages for the first chunk and as pageattr doesn't know about the alias it ends up updating page attributes of the original mapping thus leaving the alises in inconsistent state which might lead to subtle data corruption. Please read the following threads for more information: http://thread.gmane.org/gmane.linux.kernel/835783 The following is the proposed fix which teaches pageattr about percpu aliases. http://thread.gmane.org/gmane.linux.kernel/837157 However, the above changes are deemed too pervasive for upstream inclusion for 2.6.30 release, so this patch essentially disables the remap allocator for the time being. Signed-off-by: Tejun Heo LKML-Reference: <4A1A0A27.4050301@kernel.org> Signed-off-by: Ingo Molnar

x86: remove duplicated code with pcpu_need_numa()

2009-04-02T04:08:05Z

Impact: clean up those code pcpu_need_numa(), should be removed. Signed-off-by: Yinghai Lu Acked-by: Tejun Heo Acked-by: David Miller LKML-Reference: <49D31770.9090502@kernel.org> Signed-off-by: Ingo Molnar

x86,percpu: fix inverted NUMA test in setup_pcpu_remap()

2009-04-02T04:08:05Z

setup_percpu_remap() is for NUMA machines yet it bailed out with -EINVAL if pcpu_need_numa(). Fix the inverted condition. This problem was reported by David Miller and verified by Yinhai Lu. Reported-by: David Miller Reported-by: Yinghai Lu Signed-off-by: Tejun Heo LKML-Reference: <49D30469.8020006@kernel.org> Signed-off-by: Ingo Molnar

percpu: generalize embedding first chunk setup helper

2009-03-10T07:27:48Z

Impact: code reorganization Separate out embedding first chunk setup helper from x86 embedding first chunk allocator and put it in mm/percpu.c. This will be used by the default percpu first chunk allocator and possibly by other archs. Signed-off-by: Tejun Heo

percpu: more flexibility for @dyn_size of pcpu_setup_first_chunk()

2009-03-10T07:27:48Z

Impact: cleanup, more flexibility for first chunk init Non-negative @dyn_size used to be allowed iff @unit_size wasn't auto. This restriction stemmed from implementation detail and made things a bit less intuitive. This patch allows @dyn_size to be specified regardless of @unit_size and swaps the positions of @dyn_size and @unit_size so that the parameter order makes more sense (static, reserved and dyn sizes followed by enclosing unit_size). While at it, add @unit_size >= PCPU_MIN_UNIT_SIZE sanity check. Signed-off-by: Tejun Heo

x86, percpu: setup reserved percpu area for x86_64

2009-03-06T05:33:59Z

Impact: fix relocation overflow during module load x86_64 uses 32bit relocations for symbol access and static percpu symbols whether in core or modules must be inside 2GB of the percpu segement base which the dynamic percpu allocator doesn't guarantee. This patch makes x86_64 reserve PERCPU_MODULE_RESERVE bytes in the first chunk so that module percpu areas are always allocated from the first chunk which is always inside the relocatable range. This problem exists for any percpu allocator but is easily triggered when using the embedding allocator because the second chunk is located beyond 2GB on it. This patch also changes the meaning of PERCPU_DYNAMIC_RESERVE such that it only indicates the size of the area to reserve for dynamic allocation as static and dynamic areas can be separate. New PERCPU_DYNAMIC_RESERVED is increased by 4k for both 32 and 64bits as the reserved area separation eats away some allocatable space and having slightly more headroom (currently between 4 and 8k after minimal boot sans module area) makes sense for common case performance. x86_32 can address anywhere from anywhere and doesn't need reserving. Mike Galbraith first reported the problem first and bisected it to the embedding percpu allocator commit. Signed-off-by: Tejun Heo Reported-by: Mike Galbraith Reported-by: Jaswinder Singh Rajput

percpu, module: implement reserved allocation and use it for module percpu variables

2009-03-06T05:33:59Z

Impact: add reserved allocation functionality and use it for module percpu variables This patch implements reserved allocation from the first chunk. When setting up the first chunk, arch can ask to set aside certain number of bytes right after the core static area which is available only through a separate reserved allocator. This will be used primarily for module static percpu variables on architectures with limited relocation range to ensure that the module perpcu symbols are inside the relocatable range. If reserved area is requested, the first chunk becomes reserved and isn't available for regular allocation. If the first chunk also includes piggy-back dynamic allocation area, a separate chunk mapping the same region is created to serve dynamic allocation. The first one is called static first chunk and the second dynamic first chunk. Although they share the page map, their different area map initializations guarantee they serve disjoint areas according to their purposes. If arch doesn't setup reserved area, reserved allocation is handled like any other allocation. Signed-off-by: Tejun Heo

x86: make embedding percpu allocator return excessive free space

2009-03-06T05:33:59Z

Impact: reduce unnecessary memory usage on certain configurations Embedding percpu allocator allocates unit_size * smp_num_possible_cpus() bytes consecutively and use it for the first chunk. However, if the static area is small, this can result in excessive prellocated free space in the first chunk due to PCPU_MIN_UNIT_SIZE restriction. This patch makes embedding percpu allocator preallocate only what's necessary as described by PERPCU_DYNAMIC_RESERVE and return the leftover to the bootmem allocator. Signed-off-by: Tejun Heo

percpu: use negative for auto for pcpu_setup_first_chunk() arguments

2009-03-06T05:33:59Z

Impact: argument semantic cleanup In pcpu_setup_first_chunk(), zero @unit_size and @dyn_size meant auto-sizing. It's okay for @unit_size as 0 doesn't make sense but 0 dynamic reserve size is valid. Alos, if arch @dyn_size is calculated from other parameters, it might end up passing in 0 @dyn_size and malfunction when the size is automatically adjusted. This patch makes both @unit_size and @dyn_size ssize_t and use -1 for auto sizing. Signed-off-by: Tejun Heo

x86, percpu: fix minor bugs in setup_percpu.c

2009-02-25T01:38:10Z

Recent changes in setup_percpu.c made a now meaningless DBG() statement fail to compile and introduced a comparison-of-different-types warning. Fix them. Compile failure is reported by Ingo Molnar. Signed-off-by: Tejun Heo Reported-by: Ingo Molnar